(i) Technical Field
A certain aspect of the embodiments discussed herein is related to a method of manufacturing a semiconductor device. Another aspect of the embodiments is related to a method of manufacturing a semiconductor device in which a GaN layer is grown on a SiC substrate.
(ii) Related Art
Semiconductor devices using a nitride semiconductor are used as power devices operating at high frequencies and at high powers. Particularly, FETs such as high electron mobility transistors (HEMTs) have been known as semiconductor devices suitable for amplification in a high-frequency band such as a microwave band, a quasi-millimeter band, or a millimeter band.
Semiconductor devices in which an AlN layer, an AlGaN layer, a GaN layer, and an electron supply layer are sequentially stacked on a Si substrate are known as semiconductor devices using a nitride semiconductor (see Japanese Patent Application Publication No. 2008-166349). It is also known that a SiC substrate, instead of a Si substrate, may be used as the substrate of a semiconductor substrate using a nitride semiconductor.
As shown in FIG. 1, there exist micropipes 12 in a SiC substrate 10. The micropipes 12 penetrate through the SiC substrate 10, and are several μm to several hundreds of μm in diameter. The micropipes 12 are orientated in various directions. In a case where a nitride semiconductor is grown on the SiC substrate 10, the micropipes 12 are not blocked and remain open in some cases. In such cases, semiconductor devices fail to achieve excellent characteristics at the portions where the micropipes 12 are left open.